1. Field
The present disclosure relates to a thin film transistor and a display panel employing the same.
2. Description of the Related Art
Thin film transistors are used in various applications. In particular, thin film transistors are used as switching and driving devices in a display field.
Recently, a thin film transistor used as an optical sensing device of an optical touch screen apparatus has been proposed. In a touch screen apparatus, if a user touches a specific position on a display screen by using a finger or a pen, a specific process may be performed by using software to determine the position, and thus the touch screen apparatus may directly receive input data on the display screen. An existing touch screen apparatus that is widely used uses a direct-touch method in which a user directly touches a screen of a display apparatus by using a finger, a pen, or the like. However, as display apparatuses become larger, when a distance between a user and a display apparatus is increased, it may be difficult to use such a direct-touch method. Optical touch screen apparatuses may perform the same function as an existing touch screen by sensing light instead of a finger or a pen. Optical touch screen apparatuses are expected to be advantageous for communication between users as well as communication between a user and a terminal.
As such, when a thin film transistor is used in a display device, performance of the thin film transistor greatly depends on a semiconductor material forming a channel layer, and performance of the channel layer greatly deteriorates due to external light or temperature. Also, when a liquid crystal display device, which is a non-emissive display device, is used as a display device, a backlight may further be included as an image forming light source. When light is incident on a channel layer, performance of the channel layer may deteriorate.